1. Field of the Invention
The present invention is related to the field of oil well drilling equipment and in particular to drilling derricks having a pipe racker with left and right side racks and a handling head for lifting and/or guiding pipes within these racks.
2. Description of the Prior Art
More and more activity is being undertaken in the field of offshore deep water drilling. Floating platforms are generally used for deep water drilling and are subject to motion. For this reason it is necessary that pipe and drill collar handling equipment must be devised so that the pipe or drill collars may be positioned quickly and accurately in the well hole. In addition, pipe or drill collars must be racked in such a manner that they will be secure even when the platform, upon which the derrick is placed, rolls or pitches or is subjected to the force of the wind.
The pipe or drill collars are typically formed into a stand which consists of three sections of pipe or drill collar linked end to end. Each stand will then be picked up and manipulated by one or more handling heads to be positioned within a rack or moved to a position for connection to the drill string. The handling heads must therefore be able to securely grasp and lift the stand and accurately move the stand to the desired position within the pipe racker while the entire structure may be rolling or pitching in a rough sea. In the prior art, the handling heads have employed a latching finger, which when opened, would open to either the left or right side. In order to space the pipe closely, pipe or drill collars would be racked on the side which was opposite to the side on which the latching finger opened. Since the well head is positioned in the center of the derrick, the pipe racker is divided into a left and right half, one on each side of the center line of the derrick. Therefore, to store the stands in each half of the pipe racker, a left and right handed handling head was required. In the prior art, this necessitates carrying two separate handling heads on the drilling platform and necessitates a time consuming changeover which is usually manually performed.
In order to avoid the necessity of carrying two handling heads for each manipulating arm, when required, the prior art has devised a rotatable guide head whereby a left opening head may be unbolted, manually rotated and rebolted to form a right opening guide head. Again, this necessitated a time consuming manual operation. Moreover, the prior art rotatable guide heads were of such a design that after rotation, the center of the handling head was not positioned on the same axis in relation to the center of the derrick in the left hand configuration as it was in the right hand configuration.
Therefore, what is needed is a handling head which may be a guide or lifting head or which may be modified to encompass only a lifting or guide head, which may operate on both the left and right hand side of the pipe racker, and which may be automatically operated. Moreover, a universal handling head is needed, which when changed from left handed to right handed operation, or vice versa, will position the pipe on the same axis in relation to the manipulating and lifting arms so that automated or computer controlled racking of the stand in the left and right hand sides of the pipe racker may be accomplished without undue complication or adjustment due to changeover of the handling head.